Dielectric resonator and dielectric filter

ABSTRACT

A dielectric resonator ( 10 ) having three surfaces formed by chamfering three ridged portions sharing an apex of a dielectric block and another three surfaces adjacent respectively thereto, in which each of the chamfered surfaces and the adjacent surfaces thereto offers an angle of 45 degrees and an area ratio of the chamfered surfaces with respect to the adjacent surfaces is 45% is mounted in a cut-off waveguide of a generally rectangular parallelopiped ( 21 ) and feeding probe ( 24 ) and ( 25 ) are provided for composing a dielectric filter.

TECHNICAL FIELD

The present invention relates to a dielectric filter used in radiocommunications, and the like at high frequency band as microwave band;quasi-microwave band, and the like and a dielectric resonator used inthe dielectric filter, and more particularly to a triple mode dielectricresonator in which three resonant modes are available in one dielectricblock and a dielectric filter using the dielectric resonator therein.

TECHNICAL BACKGROUND

Conventionally, a dielectric filter which providing a cut-off waveguidewith cylindrical or rectangular parallelopiped dielectrics disposingsuccessively therein and utilizing resonance of a cylindrical TE01 δmode or a rectangular TE11 δ mode of dielectrics is utilized widely infilters requiring low loss and size reduction, because the dielectricfilter has high unloaded Q and can be reduced in size easier thanwaveguide type filter (a first conventional example). A resonance of themode is generated by an electric field repeating reflections at aninterface surface of the dielectric resonator and the air. The resonantfrequency of dielectric resonator is inversely proportional to thelength of the resonator and square root of dielectric constant, so thatthe larger the dielectric constant is, the smaller the resonator is. Anda magnetic field generated by the resonance excites a resonator on thenext stage and the excitation corresponds to the coupling between stagesof the dielectric filter. As a magnitude of the coupling is mainlydetermined by the distance between resonators, the farther the distanceis, the weaker the coupling is. As adjusting means for theabove-mentioned dielectric filter, a method of adjusting the resonantfrequency by a screw in a direction orthogonal to the reflecting surfaceof the magnetic field or a method of adjusting the coupling between theresonators by a screw, and the like are adoptable.

And there is also a dielectric filter utilizing a dual mode dielectricresonator in order to achieve size reduction (a second conventionalexample). The above-mentioned dielectric resonator provides tworesonance by one resonator, in which a cylindrical dielectric resonatoris disposed in the center of a cylindrical waveguide by justifying theaxes of the cylinders, for example, and two resonance (HE11 δ) generatedin two directions orthogonal to the axes of the cylinders are coupled bydisturbing the electromagnetic field of the resonance from the waveguideside using means as screws, and the like.

As the description about a first conventional example above, theresonant frequency of the resonator by a cylindrical TE01 δ mode or arectangular TE11 δ mode of dielectrics depends on dielectric constantand the size of dielectrics and a resonator can be smaller when thedielectric constant gets larger, accordingly the simplest method ofreducing size of the filter utilizing the dielectric resonator is toraise the dielectric constant of dielectrics.

However, as dielectrics with low dielectric loss used in microwaveregion generally has a characteristic that dielectric loss thereofincreases as dielectric constant becomes higher, size reduction of thefilter maintaining insertion loss low has a certain limitation. Further,as dielectrics with low loss as mentioned above is expensive,accordingly the filter becomes expensive when the filter provides morestages, that is, provides more dielectrics used therein.

And a filter relative to a second conventional example utilizing HE11 δdual mode dielectric resonator for size reduction has a problem thatlots of undesired modes excited in the vicinity of pass band result inspurious characteristic deteriorated easily, because HE11 δ is not thedominant mode.

On the other hand, for example, in the event that a dielectric filterused in microwave communications, and the like is composed, it isconventionally hard to reduce size and weight of a dielectric filter,because many resonators and each spaces between the resonators occupieslarge amount of volume and weight according to the requirement of oneresonator for one resonance and space for coupling between eachresonator. Therefore, there still is a problem that the dielectricfilter is unavoidably composed complicated and large, even though it isa band pass filter using dielectric resonators of relatively small size.

Consequently, composing a dielectric filter using dielectric resonatorscapable of multiple mode resonance is proposed to realize a band passfilter with a very small and simple composition exploiting advantages inusing dielectric resonators fully. For example, size reduction of a bandpass filter having a double-tuned band characteristic by varying theresonant frequency of the two resonance modes to each other is proposedin unexamined Japanese Patent Publication No. Hei 7-58516, in whichdegenerate coupling of two resonance modes with respect to TE101 andTE01 δ modes is disclosed (a third conventional example). And a multiplemode dielectric resonator capable of generating TM01 δ mode and TE01 δmode which are generated on a surface parallel to each surface (x-ysurface, y-z surface, x-z surface) in a rectangular coordinate system ina generally rectangular parallelopiped shaped dielectric block isproposed in unexamined Japanese Patent Publication No. Hei 11-145704 (afourth conventional example).

However, it is still unavoidable that a dielectric resonator occupies alarge amount of volume in a band pass filter requiring a resonator ofmultiple stages, even though the degenerate coupling of two resonancemodes relative to the above-mentioned third conventional example asdescribed in unexamined Japanese Patent Publication No. Hei 7-58516 isutilized. And even a triple mode dielectric resonator relative to thefourth example as described in unexamined Japanese Patent PublicationNo. Hei 11-145704 has a problem that the manufacturing process becomescomplicated, because utilization of hybrid coupling of TM01 δ mode andTE01 δ mode which are orthogonal spatially requires the thickness ofdielectric resonator to be adjusted to resonant frequency.

It is therefore a first object of the present invention to realize adielectric filter capable of reducing the number of dielectricresonators to a large extent, aiming at size reduction and costreduction and providing favorable out-of-band characteristic byincorporating the mode which has been undesired into the band andactivating the mode as a portion of resonance necessary for filtercharacteristic exploiting advantages that unloaded Q of the dielectricfilter by a cylindrical TE01 δ ode or a rectangular TE11 δ mode relativeto a first and a second conventional examples is high.

And a second object of the present invention is to solve the problem ofthe above-mentioned third and fourth conventional examples and toprovide a very small dielectric resonator with simple composition inspite of enabling a triple mode resonance and a dielectric filter usingthe above-mentioned dielectric resonator.

DISCLOSURE OF THE INVENTION

The present invention aims at size reduction of dielectric filter byusing three resonant modes in one dielectric block in order to achieve afirst object of the above-mentioned present invention. That is, in ablock of a generally rectangular parallelopiped consisting of dielectricmaterial, three resonant modes in a single dielectric block can becoupled by chamfering a ridge portion of the dielectric block andanother ridge portion unparallel thereto.

That is, the dielectric resonator claimed in claim 1 is characterized incombining three resonant modes of the above-mentioned dielectric blockby removing one ridge portion and another ridge portion unparallelthereto in a block of a generally rectangular parallelopiped.

It is apparent from physical symmetry characteristics that a rectangularTE11 δ mode can exist in each of three orthogonal axial direction in ablock of a generally rectangular parallelopiped. In a conventionaldielectric filter using TE11 δ mode or HE11 δ mode, the filter iscomposed using only one or two resonance out of the above-mentionedresonance of three axial direction, while the rest of the resonanceexerts a harmful effect as undesired resonance. In the presentinvention, the rest of the resonance is utilized positively so that oneresonator acts as three resonators.

And a dielectric filter claimed in claim 2 is characterized in disposingat least one dielectric resonator claimed in claim 1 in a cut-offwaveguide.

Because a small dielectric filter with low insertion loss can bemanufactured by composing a filter in which one or more of theabove-mentioned dielectric resonators are disposed in the cut-offwaveguide.

Further, a dielectric filter claimed in claim 3 is characterized indisposing two or more of the above-mentioned dielectric resonators inthe above-mentioned cut-off waveguide and providing means for partitionconsisting of electric conductive material between the above-mentioneddielectric resonators.

Because, in the event of using plural of resonators, it becomes possibleto adjust the coupling of each mode between resonators properly, to takerequired coupling for the pass band characteristics and to form anattenuation pole out of the pass band by providing conductive partitionsbetween each of the resonators.

And a dielectric filter claimed in claim 4 is characterized in disposinga metal rod contacting with the above-mentioned waveguide by one endparallel to a side surface of the above-mentioned dielectric resonatorin a position away from the above-mentioned side surface by apredetermined distance, in which resonant frequency of each resonanceand the coupling between each of the resonance are adjustable dependingon the length of the above-mentioned metal rod.

Because, a filter using a triple mode dielectric resonator according tothe present invention is capable of adjusting resonant frequency and theamount of coupling by putting a metal rod as a screw from the cut-offwaveguide parallel to the side surface of the dielectric resonator inthe position away from the side surface of the dielectric resonator by apredetermined distance and occupying adjustable range of the filterwidely by combining above-mentioned operation with conventional meansfor adjusting.

Incidentally, a dielectric filter claimed in claim 5 is characterized infurther installing a resonator other than the dielectric resonatorclaimed in claim 1 in the above-mentioned waveguide as well.

Because, a small filter with an arbitrary number of stage can becomposed by combining the triple mode dielectric resonator according tothe present invention and resonators of dielectrics TE01 δ mode or TEMmode by metallic conductor, and the like. Besides, out-of-bandcharacteristics all over the filter can be improved by using a resonatorwith less undesired resonance or with undesired resonance located awayfrom the necessary band as the above-mentioned combined resonator.

On the other hand, in the present invention, a dielectric resonator iscomposed of a dielectric block of a generally rectangular parallelopipedwith three ridge portions chamfered thereof and TE01 δ mode is generatedon the electro-magnetically individual three surfaces of theabove-mentioned dielectric block as claimed in claim 6 in order toachieve the above-mentioned second object of the present invention.

Incidentally, it is preferable for the above-mentioned dielectric blockto be mounted in a cut-off waveguide of a generally rectangularparallelopiped as claimed in claim 7.

And a dielectric resonator claimed in claim 8 is characterized in havingthree surfaces of A1, A2, A3 (hereafter called surfaces A) formed bychamfering three ridge portions sharing an apex of the above-mentioneddielectric block and three surfaces of B1, B2, B3 (hereafter calledsurfaces B) adjacent to each of the surfaces A respectively, in which anangle between 40 degrees and 50 degrees, both inclusive, is offered bythe surfaces A and B and an area ratio of the above-mentioned surfaces Awith respect to the surfaces B stands between 1% and 200%, bothinclusive.

Further, a dielectric resonator claimed in claim 9 is characterized inhaving three surfaces A formed by chamfering three ridge portionssharing an apex of the above-mentioned dielectric block, another threesurfaces of A′4, A′5, A′6 (hereafter called surfaces A′) formed bychamfering three ridge portions sharing another apex on a diagonal lineof the above-mentioned point, another three surfaces of B′1, B′2, B′3(hereafter called surfaces B′) adjacent to each of surfaces A andsurfaces A′ respectively and still another three surfaces of C′1 C′2 C′3(hereafter called surfaces C′) adjacent to each of surfaces A andsurfaces A′ respectively, in which an angle between 40 degrees and 50degrees, both inclusive, is offered by the surfaces A and B′ or by thesurfaces A′ and C′ and an area ratio of the above-mentioned surfaces Awith respect to the above-mentioned surfaces B′ or an area ratio of theabove-mentioned surfaces A′ with respect to the above-mentioned surfacesC′ stand between 1% and 200%, both inclusive, respectively.

On the other hand, a dielectric filter claimed in claim 10 is adielectric filter using a dielectric resonator, in which an anglebetween 40 degrees and 50 degrees, both inclusive, is offered by theabove-mentioned three surfaces A or A′ and other three surfaces B or B′adjacent thereto respectively and the surfaces A or A′ and surfaces B orB′ adjacent thereto respectively have three opposing surfaces of C1, C2,C3 (hereafter called surfaces C) or the surfaces C′ and characterized inproviding a feeding probe near the surfaces B and B′, the surfaces B′and B′, the surfaces C and C′, or the surfaces C′ and C′.

And a dielectric filter claimed in claim 11 is a dielectric filter usinga dielectric resonator having the above-mentioned three surfaces Aformed by chamfering three ridge portion sharing an apex of theabove-mentioned dielectric block, another three surfaces B adjacent tothe above-mentioned three surfaces A forming an angle of 40 degreesthrough 50 degrees and three surfaces C opposing to the above-mentionedthree surfaces B respectively, in which a feeding probe is provided onthe surfaces B and surfaces C.

Incidentally, as a dielectric filter claimed in claim 12, an angleoffered by direction p and p′ of the feeding probe with respect to thex, y, z axes of the above-mentioned dielectric resonator are variablewithin the range of −45 degrees through +45 degrees while in use.

And as a dielectric filter claimed in claim 13, frequency andattenuation generating the attenuation pole at a lower side band can bevaried by varying a position for providing a feeding probe on theabove-mentioned surfaces B and a position for providing a feeding probeon the above-mentioned surfaces C respectively.

Here, either of rod-type as claimed in claim 14 or loop-type as claimedin claim 15 is acceptable as the above-mentioned feeding probe.

Further, as claimed in claim 16, a dielectric filter capable of beingapplied to various kinds of application can be composed by mounting twoor more of the above-mentioned dielectric resonators in theabove-mentioned cut-off waveguide of a generally rectangularparallelopiped therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram for showing a triple mode dielectricresonator relative to a first preferred embodiment of the presentinvention,

FIG. 2 is a diagram for illustrating resonance of rectangular TE11 δmode, (a) is indicating a direction to which an electric field acts and(b) is indicating a direction to which a magnetic field actsrespectively,

FIG. 3 is a diagram for illustrating the principle of a resonator whichexcites three resonance successively, (a) is indicating resonance of adirection z is on a first stage of a filter, (b) is indicating resonancein a direction x on a second stage and (c) is indicating resonance in adirection yon a third stage,

FIG. 4 is a diagram for illustrating how the coupling can be varied inthe event of varying the size of the ridge portion to be chamfered, (a)is showing a graph indicating the result and (b) is showing how to takea size C of the ridge portion to be chamfered and a size L of wholesurface including the above-mentioned chamfered portion,

FIG. 5 is a perspective diagram for showing a dielectric filter of theexample 1 utilizing a triple mode dielectric resonator,

FIG. 6 is a diagram for showing an example of characteristics of thedielectric filter shown in FIG. 5, (a) is showing a relation betweeninsertion loss and return loss with frequency and (b) is showing a wideband characteristics of transmission loss,

FIG. 7 is a perspective diagram for showing a comparative example 1 of adielectric filter with three stages utilizing conventional TE11 δ mode,

FIG. 8 is a perspective diagram for showing a comparative example 2 of adielectric filter utilizing conventional HE11 δ dual mode,

FIG. 9 is showing pass band characteristics of the dielectric filter ofthe comparative example 2 shown in FIG. 8,

FIG. 10 is a perspective diagram for showing a dielectric filter of anexample 2 utilizing two triple mode dielectric resonators,

FIG. 11 is a perspective diagram for showing a dielectric filter of anexample 3 providing a dielectric filter utilizing two triple modedielectric resonators with a metallic partition between two dielectricblocks,

FIG. 11A shows the dielectric filter of FIG. 11 as configured using aloop-type feeding probes 8.

FIG. 12 is a diagram for showing a frequency characteristic of thedielectric filter shown in FIG. 11,

FIG. 13 is a diagram showing a method of adjusting the dielectric filterby using a metal rod,

FIG. 14 is a perspective diagram for showing a dielectric filter witheight stages relative to the example 5 consisting of a combination of atriple mode dielectric resonator of the present invention and a metallicTEM mode resonator,

FIG. 15 is a diagram for illustrating a triple mode dielectric resonatorrelative to a second preferred embodiment of the present invention, (a)is a diagram for showing a basic composition of the triple modedielectric resonator, (b) is a diagram for showing planes existing eachelectric field of the triple mode resonance in the dielectric resonatorand (c) is a diagram for showing a method of exciting a single mode (inother word, exciting in a degenerated state) in the dielectricresonator,

FIG. 16 is a diagram for showing pass band characteristics and returnloss in the event of exciting a single mode (in other word, exciting ina degenerated state) as shown in FIG. 5(c),

FIG. 17 is a diagram for showing a dielectric resonator of an example 1,(a) is a perspective view of the dielectric resonator observed from acertain point of view and (b) is a perspective view of the dielectricresonator observed from another point of view,

FIG. 18 is a diagram for showing a composition of the dielectric filtermounting a dielectric resonator of the example 1 therein,

FIG. 19 is showing pass band characteristics and return loss of adielectric filter shown in FIG. 18,

FIG. 20 is a diagram for showing a dielectric resonator of the example2, (a) is a perspective view of the dielectric resonator observed from acertain point of view and (b) is a perspective view of the dielectricresonator observed from another point of view.

FIG. 21 is a diagram for showing a relation between a dielectricresonator and a feeding probe of the example 3,

FIG. 22 is a diagram for showing a relation between a dielectricresonator and a feeding probe of an example 4, (a) is a diagram forshowing main portion of the dielectric filter of the example 4 and (b)is a diagram for showing an installing position of the feeding probe,

FIG. 23 is a diagram for showing attenuation characteristics of thedielectric filter of the example 4 and

FIG. 24 is a diagram for illustrating an event of using pluraldielectric resonators, (a) is a diagram for showing an example 5 usingtwo dielectric resonators and (b) is a diagram for showing an example 6applying four dielectric resonators to a duplexer.

PREFERRED EMBODIMENT FOR CARRYING OUT THE PRESENT INVENTION

Referring to the drawings, explanation will be made for describing thepresent invention in detail, as follows.

At first, a first preferred embodiment of the present invention isdescribed. FIG. 1 is a perspective diagram for showing a triple modedielectric resonator relative to a first preferred embodiment of thepresent invention. The triple mode dielectric resonator relative to thepresent preferred embodiment is composed of combination of threeresonant modes in one dielectric block 1 by having a surface 2 a formedby chamfering a ridge portion of a dielectric block 1 of a generallyrectangular parallelopiped and a surface 2 b formed by chamferinganother ridge portion which is not parallel to the above-mentioned ridgeportion. Incidentally, though axes x, y, z is shown separately from thedielectric block 1 in FIG. 1, the axes x, y, z are in a relation to beorthogonal to each of two surfaces of the dielectric block 1 of agenerally rectangular parallelopiped. And the relation is taken over inthe following drawings.

That is, now, in the orthogonal x-y-z coordinate system, the electricfield is excited initially so that a direction z corresponds to apropagation direction of TE wave. Then an electric field repeatsreflections in the direction z by 180-degrees reflection of the electricfield at an interface surface of the dielectrics and the air and excitesresonance of rectangular TE11 δ mode at a certain frequency shown inFIGS. 2(a) and (b). However, as shown in FIG. 1, when the dielectricblock 1 has the surface 2 a which is formed by chamfering a ridgeportion parallel to the axis y, a tangent component (component y) of theelectric field reflects in a 90-degrees direction on the surface 2 a andpropagates in the direction x. That is, component y in the propagationdirection z reflects on the surface 2 a and becomes component y in thepropagation direction x. Electric wave generated in the direction x alsorepeats reflections at the interface surface similar to the direction zand excites resonance. According to the similar principle, when thedielectric block 1 has the surface 2 b which is formed by chamfering aridge portion parallel to the axis z, resonance in the direction y isexcited and three resonance are excited successively by one resonator.What described above is the principle of the combination. Though theactual electric field in a resonator are degenerated so that componentsin three directions can exist concurrently, it is understandable thatthe direction z is on a first stage, as shown in FIG. 3(a), thedirection x is on a second stage, as shown in FIG. 3(b), the direction yis on a third stage, as shown in FIG. 3(c). When the dielectric block isa cube, resonant frequency on the second stage is raised higher. Foradjusting three resonance frequencies, the size of the dielectric block1 can be shortened on the second stage, that is, in the direction x. Andwith regard to the coupling, it can be understood that the surface 2 awith a chamfered ridge portion is a coupling of the first and the secondstages and the surface 2 b with a chamfered ridge portion is acombination of, the second and the third coupling.

The result of checking for how the coupling varies in the event ofchanging the size of chamfering the above-mentioned ridge portion isshown in FIG. 4. Here, by taking a size C of the chamfered ridge portionof the dielectric block 1 of a generally rectangular parallelopiped anda size L of the whole surface including the chamfered portion, variationof coefficients of coupling is checked for in four events of varyingC/L. As shown in FIG. 4(a), as an occupied rate of the size L of thewhole by the size C of the chamfered ridge portion goes up, so does thecoefficients of the coupling monotonously. Therefore, the coupling canbe intensified, as the size of the chamfered ridge portion is takenlarger in the dielectric block 1.

EXAMPLE 1

FIG. 5 is a perspective diagram of a dielectric filter of an example 1in which one of the above-mentioned triple mode dielectric resonator isused. That is, as shown in FIG. 5, the dielectric filter of the presentexample is composed of a triple mode dielectric resonator 50 disposed ina cut-off wave guide 3, in which three resonant modes of a dielectricblock 1 of a generally rectangular parallelopiped are coupled by forminga surface 2 a by chamfering a ridge portion and a surface 2 b bychamfering a ridge portion on the dielectric block 1 and two rod-typeantennas 8, 8 having a tip respectively opened by input-output terminals9, 9 are provided as means for excitation. In the dielectric filter ofthe example 1, the antennas 8, 8 with an open tip are used as means forexcitation of the dielectric resonator 50. Actually, the dielectricresonator 50 is supported by dielectrics with low dielectric constant,and the like in order not to contact with the cut-off waveguide 3, whilethe dielectrics with low dielectric constant is abbreviated in thepresent diagram. Characteristics example of the dielectric filter shownin FIG. 5 is shown in FIGS. 6(a) and (b). As shown in FIG. 6(a), threepoles of return loss appear and that indicates characteristicscorresponding to the characteristics of a filter with three stages isobtained. And as shown in FIG. 6(b), it is apparent that two attenuationpoles 62, 64 are generated on a side of higher frequency than centerfrequency.

The inset in FIG. 5 shows exemplarily a feeding probe as being aloop-type probe rather than a rod-type probe. FIG. 11A additionallyshows the loop-type feeding probe 8 as specifically incorporated in anexemplary embodiment of the present invention.

COMPARATIVE EXAMPLE 1

FIG. 7 is a perspective diagram for showing a comparative example 1 of adielectric filter with three stages using a conventional TE11 δ mode.That is, the dielectric filter of the comparative example 1 is composedof three dielectric blocks 1 putting a predetermined distance to eachother disposes in a longitudinal cut-off waveguide 3 and rod-typeantennas 8, 8 having a tip respectively opened by input-output terminals9, 9 provided as means for excitation at both ends in a longitudinaldirection of the cut-off waveguide 3. And screws 4, 4 having one endrespectively contacting with the cut-off waveguide 3 are disposedbetween each of three dielectric blocks 1 in order to adjust thecoupling between the dielectrics. Incidentally, 40 indicates mounts forsupporting each resonator (dielectric block 1) and resonant frequency ofeach resonator (dielectric block 1) is adjusted by each metal rod 42.

With regard to volume of the dielectric block 1, the dielectric filteraccording to the example 1 shown in FIG. 5 is larger to some extent thanthe one according to the comparative example 1 shown in theabove-mentioned FIG. 7, though a certain amount of distancecorresponding to the coupling is required between a dielectric block 1and another dielectric block 1, as shown in FIG. 7. As characteristicscorresponding to a filter with triple stages can be obtained by onedielectric block 1 in the dielectric filter according to the example 1shown in FIG. 5, the above-mentioned distance is not required and thevolume of whole filter is possibly one third of the comparativeexample 1. As mentioned above, in the example 1, it is possible forrealizing a small dielectric filter using a triple mode dielectricresonator.

COMPARATIVE EXAMPLE 2

FIG. 8 is a perspective diagram for showing a comparative example 2 of adielectric filter using a conventional HE11 δ dual mode. That is, thedielectric filter is composed of a cylindrical dielectric block 1supported by dielectrics with low dielectric constant, and the like (notshown) in order not to contact with a cut-off waveguide 3 disposed inthe cylindrical cut-off waveguide 3 and rod-type antennas 8, 8 having atip respectively opened by input-output terminals 9, 9 provided at bothends of the cut-off waveguide 3 varying the angles to each other. Tworesonance in the dual mode dielectric resonator are adjusted with thecoupling by a metal rod 13. Pass band characteristics of the dielectricfilter of the comparative example 2 shown in FIG. 8 are shown in FIG. 9.Incidentally, FIG. 9 shows the same band as the FIG. 6.

As shown in reference numeral 92 of FIG. 9, undesired resonance isexcited near the high frequency side of the pass band in the dielectricfilter of the comparative example 2. On the contrary, in the dielectricfilter according to the example 1 mentioned above, abrupt attenuationpoles 62, 64 are generated on the high frequency side of the pass band,which appears the dielectric filter has excellent characteristics as afilter.

EXAMPLE 2

FIG. 10 is a perspective diagram of a dielectric filter of an example 2utilizing two of the above-mentioned triple mode dielectric resonatorstherein. That is, the dielectric filter of the example 2 is composed oftwo of the triple mode dielectric resonators shown in FIG. 1 putting apredetermined distance to each other disposed in a longitudinal cut-offwaveguide 3 and rod-type antennas 8, antennas 8 having both end surfacesopened by input-output terminals 9, terminals 9 provided in a directionof axis x from the above-mentioned both end surfaces in longitudinaldirection of the cut-off waveguide 3 respectively. A screw 4 contactingwith upper surface of the cut-off waveguide 3 by one end is disposedbetween the two triple mode dielectric resonators in order to adjust thecoupling between the dielectrics. Exemplary mounts 3 a for supportingeach resonator (dielectric block 1) are shown.

In the dielectric filter of the example 2, two of the triple modedielectric resonators are provided, which makes totally six stages offilter. In FIG. 10, a metal rod (screw) 4 is inserted between theresonators in order to couple the two dielectric resonators strongly byresonance in the direction y.

EXAMPLE 3

FIG. 11 is a perspective diagram of a dielectric filter of an example 3which is a dielectric filter utilizing the above-mentioned triple modedielectric resonators providing a metallic partition 5 between twodielectric blocks 1 therein. That is, in the same manner as theabove-mentioned example 2, the dielectric filter of the example 3 iscomposed of two of the triple mode dielectric resonators shown in FIG. 1disposed in a longitudinal cut-off waveguide 3 and rod-type antennas 8,8 having both end surfaces opened by input-output terminals 9, 9provided in a direction of axis x from the above-mentioned both endsurfaces in longitudinal direction of the cut-off waveguiderespectively. In the present example, a metallic partition 5 is providedinstead of a screw 4 of the example 2 between the two dielectricresonators. And as shown in FIG. 11, a surface 2 b having theabove-mentioned another ridge portion chamfered on one side of thedielectric block 1 is formed in a different position from the surface ofthe example 2 shown in FIG. 10. Incidentally, mounts for supporting eachresonator (dielectric block 1) are abbreviated in the present diagram aswell.

A frequency characteristic of the dielectric filter is shown in FIG. 12.In the dielectric filter of the example 3, a coupling between resonatorsby resonance in direction x and direction z can be weakened by themetallic partition 5 and the coupling between the resonators can bemainly obtained by the resonance in direction y. And it is possible forproviding an attenuation pole in any position arbitrarily by varying theposition of the metallic partition 5 and the direction of eachdielectric block 1. As shown in FIG. 12, attenuation poles 122, 124 canbe provided respectively on both of low frequency side and highfrequency side of the pass band by using a shape of resonator of theexample 3 shown in FIG. 11, means for excitation and metallic partition5.

EXAMPLE 4

FIG. 13 is a diagram for showing a method of adjusting theabove-mentioned dielectric filter by a metal rod. Actually, a screw isused as a metal rod and the adjustment is conducted by putting in andout of the screw. The metal rod acts on a magnetic field leaking fromdielectrics. As the metal rod in the position of 6 a in FIG. 13 hasinterlinkage with magnetic flux of the resonance in the event ofresonance in direction x, the magnetic field is intensified and resonantfrequency becomes lower. The phenomenon is equal to a growth ofequivalent inductance in a parallel resonant circuit. In the samemanner, 6 b lowers the resonant frequency of y direction.Conventionally, as a metal rod in a position of 6 c raises the resonantfrequency, frequency can be adjusted in wide range by combination of theadjustment in the three directions x, y, z. With regard to the coupling,as 7 a weaken the coupling of resonance in direction x and in directiony while 7 b works for intensifying the coupling, adjustable range iswide. As mentioned above, because of a post-adjustment by using a metalrod, a precision required for sizes or dielectric constant of adielectric block in manufacturing a resonator can be alleviated andmanufacturing cost can be saved in the result.

EXAMPLE 5

FIG. 14 is a perspective diagram for showing a dielectric filter witheight stages composed of combination of a triple mode dielectricresonator of the present invention and a TEM mode resonator made ofmetal relative to an example 5. That is, the dielectric filter of theexample 5 is composed of two of the triple mode dielectric resonatorsshown in FIG. 1 putting a predetermined distance to each other disposesin a cut-off waveguide 3 and a TEM mode resonator 41 made of metaldisposed on both sides of the resonators. Incidentally, rod-typeantennas 8, 8 opened by input-output terminals 9, 9 are provided in adirection of axis y at both end portions of the cut-off waveguide 3. Inthe present invention, totally three metallic partitions 5 are providedbetween the two triple mode dielectric resonators and between eachtriple mode dielectric resonator and the TEM mode resonator 41.Incidentally, mounts for supporting each resonator are abbreviated inthe present diagram as well. When a filter is manufactured by using onlya triple mode dielectric resonator, the filter can be composed of stagesby multiples of three, however, a filter composed of stages of arbitrarynumbers can be composed by combining the triple mode dielectricresonator of the present invention and, for example, a resonator ofsingle TE01 δ mode of dielectrics according to a prior art, and thelike. And as shown in FIG. 14, undesired resonance can be suppressed bycombing the TEM mode resonator 41 instead.

Next, a second preferred embodiment of the present invention will bedescribed as follows.

FIG. 15(a) is a diagram for showing a fundamental composition of atriple mode dielectric resonator relative to the second preferredembodiment of the present invention and FIG. 15(b) is a diagram forshowing planes existing each electric field of the triple mode resonancein the dielectric resonator shown in FIG. 15(a).

As shown in FIG. 15(a), the dielectric resonator 10 of the presentpreferred embodiment consists of dielectric blocks generally cube-typewith three ridge portions chamfered and characterized in generating TE01δ mode in electro-magnetically independent three surfaces m1, m2, m3 ofthe dielectric block, as shown in FIG. 15(b). Incidentally, theelectro-magnetically independent three resonant modes are generated oneach surface of m1, m2, m3 and an angle of 60.0 degrees is offeredbetween each surface of m1, m2, m3, in FIG. 15(b).

FIG. 15(c) is a diagram for showing a method of exciting a single mode(in other word, exciting in the degenerated state) in the dielectricresonator shown in FIG. 15(a). As shown in FIG. 15(c), feeding probes 24and 25, for example, are disposed in the same direction on an opposingsurface to the dielectric block to excite a single mode.

FIG. 16 is a diagram for showing pass band characteristics in the eventof exciting only a single mode (in other word, exciting in thedegenerated state), as FIG. 15(c). In FIG. 16, the pass bandcharacteristics in the above-mentioned event is indicated by a solidline and return loss is indicated by a dotted line respectively.

As it is apparent from FIG. 16, all three resonant modes are TE01 δ modeand have the similar resonant frequency of approximately 1.935 [GHz] inthe triple mode dielectric resonator of the present preferredembodiment.

EXAMPLE 6

Dielectric resonators of the present example are shown in FIGS. 17(a)and (b). FIGS. 17(a) and (b) are diagrams for showing the samedielectric resonator 10 observed from different viewpoints respectively.Incidentally, a dielectric block consisting of dielectric materials ofBaO—TiO2 system providing relative dielectric constant ∈γ of 37 is usedin the dielectric resonator 10 of the present example.

For manufacturing the dielectric resonator 10 of the present example,three ridge portions sharing one point of a dielectric block consistingof a cube with a side of 22 mm (22 mm×22 mm×22 mm) are chamfered inorder to offer an angle of 45 degrees to the surface of the dielectricblock and each surface of A1, A2, A3 and each surface of A1, A2, A3 isformed in plane having a width of approximately 7 mm respectively, asshown in FIG. 17(a). As a result, there are portions of the threesurfaces of the original cube remained non-chamfered and a surface B1adjacent to the surfaces A2, A3, a surface B2 adjacent to the surfacesA1, A3 and a surface BS adjacent to the surfaces A1, A2 are respectivelyformed. The surfaces B1, B2, B3 are squares with a side of 17 mm (17mm×17 mm). Therefore, in the present example, area ratios of thesurfaces A1, A2, A3 with respect to the surfaces B1, B2, B3 respectivelyare approximately 45%.

Further, as shown in FIG. 17, each of surfaces C (surface C2 opposing tosurface B1, surface C1 opposing to surface B3, surface C3 opposing:tosurface B2) opposing to the surfaces B is shaped in a square with a sideof 22 mm (22 mm×22 mm) having one corner clipped by an isoscelestriangle with two sides of 5 mm and one side of 7 mm. Though the portionin which the surfaces A (A1, A2, A3) transposition is formed in atriangular cone, there is no problem in the characteristic to chamferthe triangular cone portion to be plane.

FIG. 18 is a diagram for illustrating a dielectric filter 20 mountingthe dielectric resonator 10 of the example 1 in a cut-off waveguide 21of a generally rectangular parallelopiped. Incidentally, though axes x,y, z are shown separately from the dielectric resonator 10 in FIG. 18,each of axes x, y, z is in relation orthogonal to each of two surfacesof the dielectric block of the original cube of the dielectric resonator10. The same thing takes place in the following drawings. The dielectricfilter 20 is formed by disposing the dielectric resonator 10 shown inFIGS. 17(a) and (b) in a cut-off waveguide 21 of a generally rectangularparallelopiped which is manufactured by processing copper (Cu) plateswith thickness of 1 mm or by grinding aluminum (Al) block to be withthickness of 3 mm. Incidentally, as shown in FIG. 18, the dielectricfilter 20 provides feeding probes 22, 23 disposed at two positionstherein. A rod-type material is used as feeding probes 24, 25. Directionp (not shown) of the two feeding probes 24 and 25 is parallel to theaxis x with respect to axes x, y, z of the dielectric resonator 10,therefore, an angle p′ (not shown) offered by the feeding probes 24 and25 is 0 degree.

In FIG. 19, pass band characteristics of the dielectric filter 20 isindicated by a solid line and return loss is indicated by a dotted line,respectively.

As shown in FIG. 19, dielectric filter 20 of the present example has apass band between 1.916 [GHz] and 1.934 [GHz], both inclusive. Further,in FIG. 19, poles of return loss 51, 52, 53 indicate that a three-stageband pass filter is formed by the dielectric filter 20 of the presentexample.

EXAMPLE 7

A dielectric resonator 11 of the present example is shown in FIGS. 20(a)and (b). FIGS. 20(a) and (b) are diagrams of the same dielectricresonator 11 observed from different points of view respectively.Incidentally, a dielectric block consists of dielectric material ofBaO—TiO2 system providing relative dielectric constant ∈γ of 37 is usedin the dielectric resonator 10 of the present example in the same manneras the example 1.

The dielectric resonator 11 of the present example has three surfaces A(A1, A2, A3) formed by chamfering three ridge portions sharing one pointof a dielectric block, as shown in FIG. 20(a) and three surfaces A′4,A′5, A′6 (hereafter called surfaces A′) further formed by chamferingthree ridge portions sharing another point on diagonal line of theabove-mentioned point. And in the present example, an angle offered bythe three surfaces A or by three surfaces A′ with other adjacent threesurfaces B′1, B′2, B′3 [refer to FIG. 20(a)] (hereafter called assurfaces B′) or with other adjacent three surfaces C′1, C′2, C′3 [referto FIG. 20(b)] (hereafter called as surfaces ′C) respectively is 45degrees.

For manufacturing a dielectric resonator 11 of the present example,three ridge portions sharing one point of a dielectric block consistingof a cube with a side of 22 mm (22 mm×22 mm×22 mm) is chamfered so thatthe surface of the dielectric block and surfaces A1, A2, A3 offers 45degrees respectively and each of the surfaces A1, A2, A3 is formed inplane with a width of 7 mm, as shown in FIG. 20(a).

Further, three ridge portion sharing another point on a diagonal line ofthe above-mentioned point is chamfered so that the surface of the.dielectric block and surfaces A4′, A5′, A6′ offers 45 degreesrespectively and each of the surfaces A4′, A5′, A6′ is formed in planewith a width of 7 mm, as shown in FIG. 20(b). As the result, there areportions of the three surfaces of the original cube remainedun-chamfered, a surface B′1 adjacent to the surfaces A2, A3, a surfaceB′2 adjacent to the surfaces A1, A3 and a surface B′3 adjacent to thesurfaces A1, A2 are respectively formed and a surface C′1 opposing tothe surface B′3, a surface C′2 opposing to the surface B′1 and a surfaceC′3 opposing to the surface B′2 are formed respectively. The surfacesB′1, B′2, B′3 are squares with a side of 17 mm (17 mm×17 mm) chamferedby one corner thereof. As the result that the corner of the surfacesB′1, B′2, B′3 is chamfered, the area ratio of the surfaces A withrespect to the surfaces B′ is approximately 48% in the present example,which gets slightly larger than the above-mentioned example 1. And theareas and forms of the surfaces C′ opposing to the surfaces B′ aresimilar to the surfaces B′.

A similar dielectric filter can be formed by mounting the dielectricresonator 11 of the present example 7 in a cut-off waveguide of agenerally rectangular parallelopiped, in the same manner as the example6.

EXAMPLE 8

A main portion of a dielectric filter of the present example is shown inFIG. 21. The dielectric filter of the present example is a dielectricfilter mounting the dielectric resonator 10 similar to the one ofexample 6 shown in FIGS. 17(a) and (b) in a cut-off waveguide if agenerally rectangular parallelopiped, but only the dielectric resonator10 and feeding probes 24 and 25 are shown in FIG. 21.

In the event that a direction p of the feeding prove 24 with respect tothe axes x, y, z of the dielectric resonator 10 swings on a x-y surfaceand an angle θ1 is 0 degree when the direction p is parallel to the axisx, the direction p can be varied within the range between −45 degreesand +45 degrees, both inclusive, and in the event that a direction p′ ofthe feeding prove 25 swings on a z-x surface and an angle θ2 is 0 degreewhen the direction p′ is parallel to the axis x, the direction p′ can bevaried within the range between −45 degrees and +45 degrees, bothinclusive. Incidentally, the angles are adjusted as θ1=5 degrees, θ2=8degrees respectively in the present example.

EXAMPLE 9

A main portion of a dielectric filter of the present example is shown inFIG. 22(a). The dielectric filter of the present example is a dielectricfilter mounting the dielectric resonator 10 similar to the one ofexample 6 shown in FIGS. 17(a) and (b) in a cut-off waveguide of agenerally rectangular parallelopiped, but only the dielectric resonator10 and feeding probes 24 and 25 are shown in FIG. 22(a).

In the present example, the feeding probes 24 and 25 are provided on thesurfaces B [the surfaces B2 in FIG. 17(a)] and the surfaces C [thesurfaces C2 in FIG. 17(b)] of the dielectric resonator 10. Positions fordisposing the feeding probes 24 and 25 are shown in FIG. 22(b). FIG.22(b) is a diagram of the dielectric resonator 10 and the feeding probes24 and 25 observed from a direction of axis x. Directions p (not shown)and p′ (not shown) of the feeding probes 24 and 25 are parallel to theaxis x, as shown in FIG. 22(b) and the feeding probes 24 can bedisplaced in parallel with the axis y and the feeding probes 25 can bedisplaced in parallel with the direction of axis z, as shown in FIG.22(b).

In FIG. 22(b), movement of the feeding probes 24 and 25 to approach toeach other is indicated as a (refer to the diagram). Here, as shown inFIG. 22(b), the amount is indicated as a=0 in the event that the feedingprobes 24 and 25 are positioned respectively on a centerline of thedielectric resonator 10.

In the present example, attenuation characteristics are measured in thefollowing three events that the feeding probes 24 and 25 are positionedrespectively on the center line of the dielectric resonator 10 [a=0],that the feeding probes 24 and 25 move 1 mm in a direction ofapproaching to each other [a=1] and that the feeding probes 24 and 25move 1 mm in a direction of leaving to each other [a=−1]. In FIG. 23,the attenuation characteristics of the dielectric filter of the presentexample are shown. At first, as shown in the diagram, in the event ofa=0, an attenuation pole 90 is generated at frequency of approximately1.873 [GHz]. Thus, the attenuation pole is obtained on a side of lowerfrequency than a center frequency, that is, on a lower side band. And itis appeared that in the event that the feeding probes 24 and 25 move inthe direction of approaching 1 mm to each other [a=1 mm], theattenuation pole 90 is generated at a frequency of approximately 1.806[GHz], that is, it moves to the side of lower frequency, comparing tothe event of a=0. On the contrary, in the event that the feeding probes24 and 25 move in the direction of leaving 1 mm to each other [a=−1 mm],the attenuation pole 90 is generated at a frequency of approximately1.90 [GHz], that is, it moves to the higher frequency side, comparing tothe event of a=0.

EXAMPLE 10

In the examples 6 through 9 above, examples using only one dielectricresonator are described, but in the present example, as shown in FIG.24, two of the dielectric resonators 10 are used and a dielectric filter100 with six stages are formed. At the time, there are two feedingprobes and the characteristics thereof can he varied in the same manneras described in the examples 8 and 9.

And though it is not shown in the diagram, it is also acceptable to usethree or more dielectric resonators 10 and the characteristics of thedielectric filter can be varied by varying the position or angle of thefeeding probe.

EXAMPLE 11

The present example is an example using four dielectric resonators 10,as shown in FIG. 24(b). The present example is an example for applying adielectric filter 150 combined for transmitting and for receiving usingtwo dielectric resonators 10 and a duplexer 200 is composed.

While specific preferred embodiments of the present invention have beendescribed above, it will be understood that the present invention is notlimited and can be applied to other preferred embodiments within thescope of invention claimed therein.

For example, though a rod-type antenna is used as a feeding probe withinthe examples 6 though 9, the similar effect can be obtained by usingloop antenna instead.

And though the angle offered by the three surfaces A formed bychamfering three ridge portions sharing one point of the dielectricblock and another three surfaces B or B′ adjacent thereto is set at 45degrees, the similar effect can be obtained by an angle in the rangebetween 40 degrees and 50 degrees, both inclusive. Further, though theangle offered by the three surfaces A′ formed by chamfering three ridgeportions sharing an apex of the dielectric block and another threesurfaces C′ adjacent thereto is set at 45 degrees, the similar effectcan be obtained by an angle within the range between 40 degrees and 50degrees, both inclusive.

Further more, though the area ratio of the surfaces A with respect tothe surfaces B is set 45%, the similar effect can be obtained by an arearatio within the range between 1% and 200%, both inclusive.

INDUSTRIAL USABILITY

According to a first preferred embodiment of the present invention, itis possible to realize a triple mode dielectric resonator which iscapable of acting as three resonators with one dielectric block, asdescribed above. And by using the triple mode dielectric resonator, itis possible to achieve size reduction of dielectric filters. In theresult of size reduction, weight and the number of required resonatorcan be reduced and the cost can be saved consequently. Besides, it isalso effective for an arbitral positioning of an attenuation poleavoiding undesired resonance, and the like.

Further, as a dielectric resonator relative to a second preferredembodiment of the present invention has a dielectric block formed bychamfering three ridge portion of a generally rectangular parallelopipedand effects a degenerate coupling of the triple mode (TE01 δ mode) ofthe equal resonant frequency generated on three surfaces which areelectro-magnetically independent of the above-mentioned dielectricblock, it is possible for a very small dielectric resonator with asimple composition to be realized easily, while resonance of triple modeis available. And by mounting the dielectric resonator relative to thesecond preferred embodiment of the present invention, for example, in acut-off waveguide of a generally rectangular parallelopiped andproviding a feeding probe therein, a small sized dielectric filter witha simple composition can be provided.

What is claimed is:
 1. A dielectric resonator in which three resonantmodes of a dielectric block of a generally rectangular parallelopipedare coupled, wherein said block has three planes formed by chamferingthree ridge portions of said dielectric block, respectively, said threechamfered ridges not being parallel to each other.
 2. A dielectricresonator claimed in claim 1 characterized in that said dielectric blockis mounted in a cut-off waveguide of a generally rectangularparallelopiped.
 3. A dielectric resonator as claimed in claim 1, whereinsaid dielectric block further has a second set of three planes formed bychamfering another three ridge portions of said dielectric block, eachsaid chamfered ridge of said second set of three chamfered ridges beingopposite a respective one of said three chamfered ridges.
 4. Adielectric resonator as claimed in claim 1, wherein said three resonantmodes are TE_(01δ) modes.
 5. A dielectric filter described by claim 1,further comprising: a feeding probe, wherein said feeding probe isloop-type.
 6. A dielectric resonator comprising a dielectric block inthe form of a generally rectangular parallelopiped having three-ridgeportions chamfered thereof and generating TE01 δ mode onelectro-magnetically independent three surfaces of said dielectric blockand having three surfaces of A1, A2, A3 (hereafter called surfaces A)formed by chamfering three ridge portions sharing a point of saiddielectric block and three surfaces of B1, B2, B3 (hereafter calledsurfaces B) adjacent to each of the surfaces A respectively, in which anangle between 40 degrees and 50 degrees, both inclusive, is offered bysaid surfaces A and said surfaces B and an area ratio of said surfaces Awith respect to said surfaces B and an area ratio of said surfaces Awith respect to said surfaces B stands between 1% and 200%, bothinclusive.
 7. A dielectric filter using the dielectric resonator claimedin claim 6, further comprising a feeding probe, characterized in that anangle offered by a direction p and p′ of the feeding probe with respectto the x, y, z axes of said dielectric resonator are variable within therange between −45 degrees and +45 degrees, both inclusive, while in use.8. A dielectric filter using the dielectric resonator claimed in claim 6characterized in having said three surfaces A formed by chamfering threeridge portions sharing an apex of said dielectric block, another threesurfaces B adjacent to said three surfaces A offering an angle between40 degrees and 50 degrees, both inclusive, and three surfaces C opposingto said three surfaces B respectively, wherein a feeding probe isprovided on the surfaces B and surfaces C.
 9. A dielectric filterclaimed in claim 8 characterized in that frequency and attenuationgenerating the attenuation pole at lower side band can be varied byvarying a position for providing a feeding probe on said surface B and aposition for providing a feeding probe on said surfaces C.
 10. Adielectric filter claimed in claim 8, 7, or 9, wherein said feedingprobe comprises a rod-type feeding probe.
 11. A dielectric resonatorcomprising a dielectric block in the form of a generally rectangularparallelopiped having three-ridge portions chamfered thereof andgenerating TE01 δ mode on electro-magnetically independent threesurfaces of said dielectric block and having three surfaces A1, A2, A3(hereafter called surfaces A) formed by chamfering three ridge portionssharing an apex of said dielectric block, another three surfaces of A′4,A′5, A′6 (hereafter called surfaces A′) formed by chamfering three ridgeportions sharing another apex on a diagonal line of said apex, anotherthree surfaces of B′1, B′2, B′3 (hereafter called surfaces B′) adjacentto each of surfaces A and surfaces A′ respectively and still anotherthree surfaces of C′1, C′2, C′3 (hereafter called surfaces C′) adjacentto each of surfaces A and surfaces A′ respectively, wherein an angle of40 degrees through 50 degrees is offered by the surfaces A and B′ or bythe surfaces A′ and C′ and an area ratio of said surfaces A with respectto surfaces B′ or an area ratio of said surfaces A′ with respect to saidsurfaces C′ stand between 1% and 200% both inclusive, respectively. 12.A dielectric filter using the dielectric resonator claimed in claim 2,6, or 11, further comprising at least two or more of said dielectricresonators in said cut-off waveguide of a generally rectangularparallelopiped.
 13. A dielectric filter using the dielectric resonatorclaimed in claim 6 or 9 characterized in that an angle between 40degrees and 50 degrees, both inclusive, is offered by said threesurfaces A or A′ formed by chamfering three ridge portion sharing anapex of said dielectric block and other three surfaces B or B′ adjacentthereto respectively and the surfaces A or A′ and surfaces B or B′adjacent thereto respectively have three opposing surfaces of C1, C2, C3(hereafter called surfaces C) or the surfaces C′ and characterized inproviding a feeding probe near the surface B and B′, the surfaces B′ andB′, the surfaces C and C′, or the surfaces C′ and C′.
 14. A dielectricfilter of claim 13, wherein said feeding probe comprises a rod-typefeeding probe.
 15. A dielectric resonator comprising: a dielectric blockhaving a generally rectangular parallelopiped shape, wherein two edgesof said dielectric block are chamfered in a manner to provide a couplingof three resonant modes of said dielectric block, wherein a firstchamfered edge is parallel to a y-axis, a second chamfered edge isparallel to a z-axis, and said first chamfered edge does not intersectsaid second chamfered edge.
 16. A dielectric filter characterized indisposing at least one dielectric resonator claimed in claim 15 in acut-off waveguide.
 17. A dielectric filter claimed in claim 16, furthercomprising a second resonator in said cut-off waveguide, said secondresonator being a type different than that described in claim
 1. 18. Adielectric filter claimed in claim 16 characterized in installinganother resonator further than said dielectric resonator in said cut-offwaveguide.
 19. A dielectric filter claimed in claim 16 characterized indisposing a metal rod contacting with said cut-off waveguide by one endin parallel with a side surface of said dielectric resonator in theposition distant by a predetermined amount from said side surface andhaving a composition in which resonant frequency of each resonance andan amount of coupling between resonance is adjustable.
 20. A dielectricfilter claimed in claim 19 characterized in installing another resonatorfurther than said dielectric resonator in said cut-off waveguide.
 21. Adielectric filter claimed in claim 16 characterized in disposing two ormore of said dielectric resonators in said cut-off waveguide andproviding a partition comprising a conductive material between saiddielectric resonators.
 22. A dielectric filter claimed in claim 21characterized in disposing a metal rod contacting with said cut-offwaveguide b one end in parallel with a side surface of said dielectricresonator in the position distant by a predetermined amount from saidside surface and having a composition in which resonant frequency ofeach resonance and an amount of coupling between resonators isadjustable.
 23. A dielectric filter claimed in claim 21 characterized ininstalling another resonator further than said dielectric resonator insaid cut-off waveguide.
 24. A dielectric resonator comprising: adielectric block having a generally rectangular parallelopiped shape,wherein three resonant modes of said dielectric block are coupled, saiddielectric resonator has a first plane formed by chamfering a single oneof a ridge portion of said dielectric block and a second plane formed bychamfering a single one of a second ridge portion of said dielectricblock, said first chamfered ridge portion not being parallel to saidsecond chamfered ridge portion, and no other ridge portion in saiddielectric block is chamfered.
 25. The dielectric resonator of claim 24,wherein a coupling amount of said three resonant modes of saiddielectric block is varied by changing dimensions of said first planeand dimension of said second plane.
 26. A dielectric resonator,comprising: a dielectric block having a generally rectangularparallelepiped shape, wherein three resonant modes of said dielectricblock are coupled, wherein said dielectric resonator has a first planeformed by chamfering a single one of a ridge portion of said dielectricblock and a second plane formed by chamfering a single one of a secondridge portion of said dielectric block, said first chamfered ridgeportion not being parallel to said second chamfered ridge portion, saidfirst chamfered ridge portion and said second chamfered ridge portionnot crossing each other, said first chamfered ridge being parallel to ay-axis, said second chamfered edge being parallel to a z-axis.
 27. Adielectric resonator, comprising: a dielectric block having a generallyrectangular parallelepiped shape, wherein three resonant modes of saiddielectric block are coupled, wherein said dielectric resonator has afirst plane formed by chamfering a single one of a ridge portion of saiddielectric block and a second plane formed by chamfering a single one ofa second ridge portion of said dielectric block, said first chamferedridge portion not being parallel to said second chamfered ridge portion,said first chamfered ridge portion and said second chamfered ridgeportion not crossing each other, and no other ridge portion in saiddielectric block is chamfered, and wherein a coupling amount of saidthree resonant modes of said dielectric block is varied by changingdimensions of said first plane and said second plane, respectively. 28.A dielectric filter, comprising: at least one dielectric resonatorincluding a dielectric block having a generally rectangularparallelepiped shape, wherein three resonant modes of said dielectricblock are coupled, wherein said dielectric resonator has a first planeformed by chamfering a single one of a ridge portion of said dielectricblock and a second plane formed by chamfering a single one of a secondridge portion of said dielectric block, said first chamfered ridgeportion not being parallel to said second chamfered ridge portion, saidfirst chamfered ridge portion being parallel to a y-axis, said secondchamfered edge being parallel to a z-axis; and a waveguide, wherein saidat least one dielectric resonator is located in said waveguide.
 29. Adielectric filter of claim 28, wherein said at least one dielectricresonator comprises a dielectric resonator of a first type, saiddielectric filter further comprising: a dielectric resonator of a secondtype, said second type dielectric resonator being coupled to said atleast one of said first type dielectric resonator.
 30. The dielectricfilter of claim 29, wherein said second type dielectric resonator has aTEM mode and comprises a metal.
 31. The dielectric filter of claim 28,further comprising: a partition comprising a conductive materialseparating two dielectric resonators in said waveguide.
 32. Thedielectric filter of claim 28, further comprising: a metal rod insertedbetween two dielectric resonators in said waveguide.
 33. The dielectricfilter of claim 28, further comprising: an exciting means as an inputterminal; and an exciting means as an output terminal.
 34. Thedielectric filter of claim 33, wherein each of said exciting meanscomprises a rod-shaped antenna of which a head portion is open.
 35. Adielectric filter, comprising: at least one dielectric resonatorincluding a dielectric block having a generally rectangularparallelepiped shape, wherein three resonant modes of said dielectricblock are coupled, wherein said dielectric resonator has a first planeformed by chamfering a single one of a ridge portion of said dielectricblock and a second plane formed by chamfering a single one of a secondridge portion of said dielectric block, said first chamfered ridgeportion not being parallel to said second chamfered ridge portion; ametal rod inserted near one of said at least one dielectric resonator,wherein each resonant frequency of each said resonant modes and eachcoupling amount between said three resonant modes are adjusted byadjusting a length of said metal rod; and a waveguide, wherein said atleast one dielectric resonator is located in said waveguide.
 36. Adielectric filter, comprising: at least one dielectric resonatorincluding a dielectric block having a generally rectangularparallelepiped shape, wherein three resonant modes of said dielectricblock are coupled, wherein said dielectric resonator has a first planeformed by chamfering a single one of a ridge portion of said dielectricblock and a second plane formed by chamfering a single one of a secondridge portion of said dielectric block, said first chamfered ridgeportion not being parallel to said second chamfered ridge portion and noother ridge portion in said dielectric block is chamfered; a waveguide,wherein said at least one dielectric resonator is located in saidwaveguide; and a dielectric member having a low dielectric constant,said dielectric member supporting said at least one dielectricresonator.
 37. A dielectric resonator comprising: a dielectric blockhaving a generally rectangular parallelopiped shape; a first chamferededge on said dielectric block, said first chamfered edge being parallelto an x-axis of said block; a second chamfered edge on said dielectricblock, said second chamfered edge being parallel to a y-axis of saidblock; and a third chamfered edge on said dielectric block, said secondchamfered edge being parallel to a z-axis of said block, wherein saidfirst, second, and third chamfered edges mutually intersect in a firstcorner of said dielectric block.
 38. The dielectric resonator of claim37, further comprising: a fourth chamfered edge on said dielectricblock, said fourth chamfered edge also being parallel to said x-axis; afifth chamfered edge on said dielectric block, said fifth chamfered edgealso being parallel to said y-axis; and a sixth chamfered edge on saiddielectric block, said sixth chamfered edge also being parallel to saidz-axis, wherein said fourth, fifth, and sixth chamfered edges mutuallyintersect in a second corner of said dielectric block, said secondcorner being diagonally opposite said first corner.
 39. A dielectricfilter comprising: at least one dielectric resonator including adielectric block having a generally rectangular parallelepiped shape,wherein three resonant modes of said dielectric block are coupled; and awaveguide containing said at least one dielectric resonator, whereinsaid dielectric resonator comprises one of the following threeconfigurations: said dielectric resonator has a first plane formed bychamfering a single one of a ridge portion of said dielectric block anda second plane formed by chamfering a single one of a second ridgeportion of said dielectric block, said first chamfered ridge portion notbeing parallel to said second chamfered ridge portion, said firstchamfered ridge portion and said second chamfered ridge portion notcrossing each other, and no other ridge portion in said dielectric blockis chamfered; said dielectric resonator has a first chamfered edge beingparallel to an x-axis of said block, a second chamfered edge beingparallel to a y-axis of said block, and a third chamfered edge on saiddielectric block being parallel to a z-axis of said block, said first,second, and third chamfered edges mutually intersecting in a corner ofsaid dielectric block; and said dielectric resonator has said firstchamfered edge, said second chamfered edge, and said third chamferededge intersecting in a first corner of said dielectric block, saiddielectric resonator further having a fourth chamfered edge also beingparallel to said x-axis, a fifth chamfered edge also being parallel tosaid y-axis, and a sixth chamfered edge on said dielectric block, saidsixth chamfered edge also being parallel to said z-axis, wherein saidfourth, fifth, and sixth chamfered edges mutually intersect in a secondcorner of said dielectric block, said second corner being diagonallyopposite said first corner.
 40. A dielectric filter according to claim39, wherein a partition is provided between said dielectric resonators,said partition being comprised of a conductive material.
 41. Adielectric filter according to claim 40, further comprising: a supportmember for each said dielectric resonator, said support member comprisedof a material having a low dielectric constant.
 42. A dielectric filteraccording to claim 39, further comprising: a first metal rod insertedbetween two of said dielectric resonators; and a second metal rodinserted near at least one said dielectric resonator, a length of saidsecond metal rod providing an adjustment for a resonant frequency ofeach said three resonant modes, said length of said second rodadditionally providing an adjustment for an amount of coupling betweensaid three resonant modes.
 43. A dielectric filter according to claim42, further comprising: a support member for each said dielectricresonator, said support member comprised of a material having a lowdielectric constant.
 44. A dielectric filter according to claim 39,further comprising: a support member for each said dielectric resonator,said support member comprised of a material having a low dielectricconstant.
 45. A dielectric filter according to claim 39, wherein a metalrod is inserted between said dielectric resonators.
 46. A dielectricfilter according to claim 39, further comprising: an exciting means usedas an input terminal; and an exciting means used as an output terminal.47. A dielectric filter according to claim 46, wherein each saidexciting means comprises a rod-shaped antenna of which a head portion isopen.
 48. A dielectric filter according to claim 46, further comprising:a support member for each said dielectric resonator, said support membercomprised of a material having a low dielectric constant.
 49. Adielectric filter according to claim 47, further comprising: a supportmember for each said dielectric resonator, said support member comprisedof a material having a low dielectric constant.
 50. A dielectric filteraccording to claim 45, further comprising: a support member for eachsaid dielectric resonator, said support member comprised of a materialhaving a low dielectric constant.
 51. A dielectric filter comprising: awaveguide; at least one dielectric resonator of a first type located insaid waveguide, said first type being a dielectric resonator including adielectric block having a generally rectangular parallelepiped shape,wherein three resonant modes of said dielectric block are coupled; andat least one dielectric resonator of a another type than said first typelocated in said waveguide, each said at least one dielectric resonatorof another type being coupled to at least one of said at least onedielectric resonator of a first type, wherein said dielectric resonatorcomprises one of the following three configurations: said dielectricresonator has a first plane formed by chamfering a single one of a ridgeportion of said dielectric block and a second plane formed by chamferinga single one of a second ridge portion of said dielectric block, saidfirst chamfered ridge portion not being parallel to said secondchamfered ridge portion, said first chamfered ridge portion and saidsecond chamfered ridge portion not crossing each other, and no otherridge portion in said dielectric block is chamfered; said dielectricresonator has a first chamfered edge being parallel to an x-axis of saidblock, a second chamfered edge being parallel to a y-axis of said block,and a third chamfered edge on said dielectric block being parallel to az-axis of said block, said first, second, and third chamfered edgesmutually intersecting in a corner of said dielectric block; and saiddielectric resonator has said first chamfered edge, said secondchamfered edge, and said third chamfered edge intersecting in a firstcorner of said dielectric block, said dielectric resonator furtherhaving a fourth chamfered edge also being parallel to said x-axis, afifth chamfered edge also being parallel to said y-axis, and a sixthchamfered edge on said dielectric block, said sixth chamfered edge alsobeing parallel to said z-axis, wherein said fourth, fifth, and sixthchamfered edges mutually intersect in a second corner of said dielectricblock, said second corner being diagonally opposite said first corner.52. A dielectric filter according to claim 51, wherein a metal rod isinserted between said dielectric resonators.
 53. A dielectric filteraccording to claim 51, wherein a partition is provided between saiddielectric resonators, said partition being comprised of a conductivematerial.
 54. A dielectric filter according to claim 51, furthercomprising: an exciting means used as an input terminal; and an excitingmeans used as an output terminal.
 55. A dielectric filter according toclaim 51, further comprising: a support member for each said dielectricresonator, said support member comprised of a material having a lowdielectric constant.
 56. A dielectric filter according to claim 51,further comprising: a first metal rod inserted between two of saiddielectric resonators; and a second metal rod inserted near at least onesaid dielectric resonator, a length of said second metal rod providingan adjustment for a resonant frequency of each said three resonantmodes, said length of said second rod additionally providing anadjustment for an amount of coupling between said three resonant modes.57. A dielectric filter according to claim 51, wherein at least one ofsaid at least one dielectric of another type comprises a resonatorhaving TEM mode and is comprised of a metal.
 58. A dielectric filteraccording to claim 57, wherein a partition is provided between saiddielectric resonators, said partition being comprised of a conductivematerial.
 59. A dielectric filter according to claim 57, furthercomprising: a support member for each said dielectric resonator, saidsupport member comprised of a material having a low dielectric constant.60. A dielectric filter according to claim 57, wherein a metal rod isinserted between said dielectric resonators.
 61. A dielectric filteraccording to claim 57, further comprising: an exciting means used as aninput terminal; and an exciting means used as an output terminal.
 62. Adielectric filter according to claim 57, further comprising: a firstmetal rod inserted between two of said dielectric resonators; and asecond metal rod inserted near at least one said dielectric resonator, alength of said second metal rod providing an adjustment for a resonantfrequency of each said three resonant modes, said length of said secondrod additionally providing an adjustment for an amount of couplingbetween said three resonant modes.